FRIDAY, Dec. 16, 2016 (HealthDay News) -- Flu season is starting to take hold across the country, and U.S. health officials are urging everyone who hasn't gotten a flu shot yet to get one now.

"Flu activity is still pretty low, but it's starting to increase," Lynnette Brammer, an epidemiologist with the U.S. Centers for Disease Control and Prevention, said Friday.

Although flu is scattered throughout the United States, the hardest hit places so far are New Jersey, New York, Puerto Rico, the Southeast and the Northwest, Brammer said. Most of the virus out there is influenza H3N2, she added. That strain is part of this year's flu vaccine, according to the CDC.

"And this week for the first time, we have data on initial hospitalizations," Brammer said. "The range of hospitalization is still low, however. As you would suspect with a H3N2 season, the highest rate right now is in the elderly."

The overall rate of hospitalizations for flu is about 2 out of every 100,000 hospitalizations. In the elderly it's 7 per every 100,000, Brammer said. Those numbers are in line with the last four to five years of flu data, she said.

Flu activity will pick up, she said. "We don't know how severe the season is going to be, so there is still time to get vaccinated. And getting vaccinated is the best way to protect yourself," she said.

This year's season is starting out much like last year, Brammer said. Currently, influenza H3N2 is the predominant strain, she said, although H1N1 is also circulating. Last year, the H3N2 virus started out as the dominant strain, only to be displaced by H1N1 as flu season hit full swing. "It ended up being an H1N1 season," she said.

"It's similar to a lot of years right now," Brammer added. "Things should start to pick up in the next few weeks, but we'll see. Last year, things didn't really pick up until the first of the year."

Last year's flu season was particularly hard on older people.

In a typical flu season, flu complications -- including pneumonia -- send more than 200,000 Americans to the hospital. Death rates linked to flu vary annually, but have gone as high as 49,000 in a year, according to the CDC.

Most of the time, flu activity peaks between December and March but can last as late as May.

This year's vaccine contains the strains currently circulating, which makes it a good match, Brammer said. The vaccine supply is also good this year, with more than 131 million doses available, she said.

How effective a vaccine is depends on how good a match it is to the strains of flu virus circulating that year. Most years, the vaccine is between 40 percent and 60 percent effective, according to the CDC.

The CDC recommends that anyone 6 months of age and older get a flu shot. "You want to make extra sure for people at high risk, including pregnant women, the elderly and anyone with a chronic medical condition," Brammer said.

Women with newborns also need to get their flu shot to help protect their infants, who can't be vaccinated until they're at least 6 months old, the CDC said.

Getting your flu shot soon is important because it can take several weeks to produce enough antibodies to give you maximum protection, officials noted.

One change this year is that the CDC's Advisory Committee on Immunization Practices does not recommend that the nasal spray vaccine be used by anyone, because it seems less effective than a shot, Brammer said.